We propose the combination of techniques that solve
multiple queries for motion planning problems with single query
planners. Our implementation uses a probabilistic roadmap method PRM
with bidirectional rapidly exploring random trees BIRRT as the local
planner. With small modifications to the standard algorithms, we
obtain a multiple query planner which is significantly faster and
more reliable than its component parts. Our method provides a smooth
spectrum between the PRM and BIRRT techniques and obtains the
advantages of both. We observed that the performance differences are
most notable in planning instances with several rigid non-convex
robots in a scene with narrow passages. This planner is in the
spirit of non-uniform sampling and refinement techniques used in
earlier work on PRM.